The Neutral Buoyancy Space Simulator is a zero-gravity space simulator located inside the George C. Marshall Space Flight Center in Huntsville, Alabama. It was designed in 1955 by the US Army to serve as a venue where engineers, astronauts, and designers could perform experiments just as if they?re in outer space.

The Neutral Buoyancy Space Simulator is highly noted in history for contributing largely to the American manned space program. It has benefitted various projects like the Apollo program, Space Shuttle, Skylab, and the Project Gemini. It also served as the only test facility that was able to help astronauts understand the concept behind the body motion under conditions were weight is irrelevant, until the Weightless Environment Training Facility was built at the Johnson Space Center in the mid-70s.

The Neutral Buoyancy Space Simulator was declared a National Historic Landmark and became a part of the National Historic Registry for its historical significance.